There are primary reinforcers and secondary reinforcers. A primary reinforcer is something like food and treats. They are biological need elements. A secondary reinforce is a human element connected to the biological need. For example, when you pat the dog on the head and give it a “good dog” compliment for a job well done, that is a secondary reinforcer if you are also giving the dog a treat. Eventually the dog will begin to accept the compliment as a positive reward for a job well done.